Article 39 director Carolyne Willow said Feltham YOI's closure was "long overdue" after young offenders aged 16 and 17 at Feltham YOI left 13 members of staff requiring hospital treatment at the weekend.
Details of how the violence began have not been released, but the institution has been criticised repeatedly over the past 30 years for confining young inmates for extended periods of time, not providing them with purposeful activity or education, and for using ineffective force and sanctions as a means of control.
A 2017 Prisons Inspectorate report stated efforts to combat "very serious" violence at Feltham including multiple assailants and the use of weapons, had been ineffective.
Last year, an annual Independent Monitoring Board report said the unit was blighted by "explosive violence", counting 405 incidents where staff had to use physical restraint in the 12 months to the end of October 2017.
An independent inquiry reviewing cases of alleged child sexual abuse at YOIs between 2009 and 2017 listed Feltham as a centre where incidents had occurred.
However, the negative appraisals were followed, in May 2018 by a further Prisons Inspectorate report which said that assaults on staff had fallen by 80 per cent and assaults on boys were down by a third.
Commenting on the latest incidents, Willow said: "The circumstances surrounding these assaults are not yet in the public domain though 20 injured officers indicates a very serious breakdown in care.
"The unsuitability of Feltham as a place to send children has been known for many decades.
"Children who cannot live safely within our communities must be held in secure settings where skilled staff have the resources and support to properly meet their needs."
Willow also called for the London Borough of Hounslow, the local authority responsible for the YOI, to begin statutory child protection investigations and take action to reduce the risks to children as a matter of urgency.
Her criticisms were echoed by Howard League for Penal Reform chief executive Frances Crook, who described Feltham as "ill-equipped to deal with troubled children".
Crook warned that calls from the centre's trade union to prosecute young people involved in the incidents would only "fuel more violence".
Young inmates identified as being involved will face adjudication hearings and could be referred to the police.
The Prison Service said: "A completely unacceptable series of assaults on staff at Feltham over the weekend led to 20 officers receiving injuries - with 13 needing hospital treatment.
"Our sympathies are with those hard-working and committed staff, who deserve to be able to carry out their jobs without facing this kind of behaviour.
"We will never tolerate violence against our staff and will push for the strongest possible punishment, which could lead to them spending more time behind bars."
The Youth Custody Service said: "The assaults on staff this weekend were completely unacceptable and we will be pushing for the strongest possible punishments."
It added that progress was being made in the face of "significant challenges", with increased numbers of custody managers and youth workers, and a specialist unit set up to provide support to its "most vulnerable young people".